This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-237271, filed Aug. 4, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a semiconductor device packaging technique, particularly to a chip pickup device and a method of manufacturing a semiconductor device used for a mounting process. More specifically, it relates to a chip pickup device and a method of manufacturing a semiconductor device for peeling chips obtained by dicing a wafer sequentially off an adhesive tape and carrying them in a process of packaging a thin chip used for an IC card, a TAG, or a three-dimensional package.
The semiconductor device used for an IC card or a portable electronic gear is limited in its mounting area and thickness. On the other hand, the functions required of the semiconductor device are now being varied more and more. In order to satisfy the requirements, the technique for mounting a semiconductor chip in a three-dimensional manner is advantageous and now being employed frequently. The three-dimensionally mounted semiconductor package is called as a stacked module, the thickness of which is equal to the conventional one. For example, the device having a flash memory and an SRAM stacked therein has already been distributed as a memory used in a portable electronic gear, and a three- or four-layered device is now being developed for distribution.
In order to mount a semiconductor chip in such a thin package, the chip conventionally having a thickness of 200 to 650 xcexcm is now being required to be have a thickness of 200 xcexcm or less. The chip used in the device having a flash memory and an SRAM stacked therein or the three- or four-layered device as mentioned above is formed as thin as 50 to 150 xcexcm. Still further, a thin chip of 50 xcexcm or less is now being demanded.
In accordance with the requirement for a thin chip, the chip is being formed very thin. However, the thinner the chip is formed, the more the cracks occur in picking up the chip, which is becoming a serious problem in the mounting process. The flexural strength of the chip is reported to be proportional to the square of the thickness of the chip. The thinner the chip is formed, the more the breaks or cracks occur in the chip.
In picking a thin silicon chip having a thickness of 40 to 200 xcexcm up with use of the conventional pickup device, very many cracks occur in the chip. A xe2x80x9ccrackxe2x80x9d means a breakage of the chip, or chipping of the periphery such as corners or edges of the chip.
A crack occurring in picking the chip up will be detailed below in conjunction with FIGS. 1, 2A, 2B, 3A to 3C, 4A to 4D, 5A to 5C, 6A to 6C, and 7A to 7H. FIG. 1 is a sectional view schematically showing a backup holder, a pin holder, and pins of the thrusting mechanism, for explaining the conventional pickup device and the method of manufacturing a semiconductor device. The pin holder 11 is formed to move vertically in the backup holder 12. When the pin holder ascends, the pins 13 thrust a chip 15 upwards with an adhesive tape therebetween to peel the chip 15 off an adhesive face 14A of the adhesive tape 14.
In general, the pins 13 are arranged symmetrically with respect to the center of the chip and along the diagonal of the chip as shown in FIG. 2A. On the upper face of the backup holder 12, through holes 16 from which the pins 13 project are formed to correspond to the arrangement of the pins, as shown in FIG. 2B.
FIGS. 3A to 3C respectively show how the conventional chip 15 having the thickness of 200 to 750 xcexcm is thrusted up, and FIGS. 4A to 4D show step by step how the chip 15 is peeled off the adhesive tape 14 by the thrust. As shown in FIGS. 3A to 3C, when the pins 13 ascend, the chip 15 is peeled off the adhesive tape 14 gradually as shown in FIGS. 4A to 4C by the unshaded areas, and completely peeled at the step shown in FIG. 4D. In the peeling process, the periphery, particularly the corners of the chip are peeled off at first by the ascending of the pins (see FIG. 4B), the peeled area increases in the area other than that around the pins (see FIG. 4C), and when the pins arrive at the highest point, the chip is completely peeled off the adhesive tape (see FIG. 4D).
If the chip is as thin as 40 to 100 xcexcm, however, the portions thrusted by the pins 13 ascend at first, and the other portions not thrusted by the pins 13 ascend behind the thrusted portions, as shown in FIGS. 5A to 5C. This is because, the chip 15 is formed so thin, and thus the chip is bent and not peeled off the adhesive tape 14. The chip remains not peeled as shown in FIGS. 6A and 6B, and thus cracks 16 occur finally. The cracks 16 occur due to the cleavage generated on the surface of the chip since the chip 15 is bent beyond the elastic limit of silicon. The cracks occurring on the surface of the chip may propagate to the rear side, and the chip 15 will be completely broken. The thinner the chip, the more the cracks occur.
FIGS. 7A to 7H respectively show the cracks of a particularly thin silicon chip having a thickness of 100 xcexcm or less. The cracks can be classified roughly into three types: a xe2x80x9cchippingxe2x80x9d mode; a xe2x80x9cbreakxe2x80x9d mode; and a xe2x80x9cpenetrationxe2x80x9d mode. The xe2x80x9cchippingxe2x80x9d mode means the condition as shown in FIGS. 7A to 7C where the corners or periphery of the chip are chipped. The xe2x80x9cbreakxe2x80x9d mode means the condition as shown in FIGS. 7D to 7G where the cracks like lines occur. The xe2x80x9cpenetrationxe2x80x9d mode means the condition as shown in FIG. 7H where only the portions thrusted by the pins upheave and crack.
As described above, the damage such as a crack are generated in the thin chip in picking up the chip with use of the conventional pickup device and the conventional method of manufacturing the semiconductor device, thereby the quality of the chip is deteriorated or the yield is decreased.
According to an aspect of the present invention there is provide a pickup device for transferring to an adhesive side of an adhesive tape mounted on a wafer ring chips separated by dicing a wafer so as to adhere the chips thereon, and sequentially peeling the chips off the adhesive tape to be carried. The pickup device comprising a thrusting mechanism configured to thrust the chips sequentially by using pins from a back side of the adhesive tape with the adhesive tape between the chips and the pins so as to peel the chips off the adhesive tape; a carrying mechanism configured to sequentially absorb the chips with use of a collet, hold the chips to be absorbed until the chips are peeled off the adhesive tape, thereafter pick the chips up by ascending the collet in order to be carried the chips to a subsequent process stage; and a controller configured to control the thrust of the chip by thrusting mechanism, the controller controlling an ascend time and a descend time of the pins, and keeping a predetermined period of a time when the pins arrive at their peak.
According to an aspect of the present invention there is provide a method of manufacturing a semiconductor device adhering on an adhesive side of an adhesive tape chips separated by dicing a wafer, and sequentially peeling the chips off the adhesive tape to be carried. The method comprising thrusting the chips by using pins from a back side of the adhesive tape with the adhesive tape between the chips and the pins; absorbing the chips by descending a collet from the adhesive side of the adhesive tape to contact the chips when the chips are peeled off the adhesive tape; and causing the pins to keep thrusting, and picking the chips up by ascending the collet after the chips are peeled off the adhesive tape, in order to be carried the chips to a subsequent process stage.
According to an aspect of the present invention there is provide a pickup device comprising a thrusting mechanism having a backup holder and a pin holder configured to vertically move in the backup holder to thrust a chip adhered to an adhesive tape by using pins with the adhesive tape between the chip and the pins; a heating mechanism configured to heat the adhesive tape to decrease adhesion of the adhesive tape when the chip is peeled off the adhesive tape; and an absorbing and carrying mechanism configured to absorb and carry the chip thrust by the pins of the thrusting mechanism.
According to an aspect of the present invention there is provide a method of manufacturing a semiconductor device adhering on an adhesive side of an adhesive tape chips separated by dicing a wafer, and sequentially peeling the chips off the adhesive tape to be carried. The method comprising blowing inert gas at a high temperature to the adhesive tape simultaneously with or immediately before thrusting of thrusting pins to each of the chips so as to decrease adhesion of the adhesive tape; and sequentially carrying the chips peeled off the adhesive tape.